1. Field
This disclosure relates to methods of servicing a wellbore. More specifically, it relates to methods of servicing a wellbore with defoaming agent compositions.
2. Background
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid, a string of pipe, e.g., casing, is run in the wellbore. The drilling fluid is then usually circulated downward through the interior of the pipe and upward through the annulus, which is located between the exterior of the pipe and the walls of the wellbore. Next, primary cementing is typically performed whereby a cement slurry is placed in the annulus and permitted to set into a hard mass (i.e., sheath) to thereby attach the string of pipe to the walls of the wellbore and seal the annulus. Subsequent secondary cementing operations may also be performed.
Many wellbore servicing fluids are foamed to facilitate their use in a wellbore servicing operation. For example, a drilling fluid may be circulated with a gas downwardly through a rotary drill pipe and drill bit connected thereto. As the aqueous solution and gas flows through the drill pipe and drill bit, the drilling fluid is foamed. Well bore cuttings generated by the drill bit are readily lifted to the surface by the foamed solution produced. When the foamed solution containing the cuttings reaches the surface, it is typically defoamed to remove the cuttings and gas. One impediment to the reuse of foamed wellbore servicing fluids is the presence of the defoamer which serves to inhibit the subsequent refoaming of the fluid. Thus, there exists an ongoing need for developing defoamers and/or defoaming strategies that facilitate the reuse of wellbore servicing fluids.